This article appears in the Fall 2017 issue of The American Prospect magazine. Subscribe here.

Before Sidney Blumenthal was a sharp-elbowed political operative for Bill and Hillary Clinton, he was a sharp-eyed political journalist. In Wrestling with His Angel, his new book on Abraham Lincoln, Blumenthal returns to those roots. He applies to the 1850s, with rewarding effect, the analytical insight and stylistic elegance that made him an indispensable writer in the 1980s on the rise of Ronald Reagan–era conservatism and the Democratic struggle to formulate a winning response. And although Blumenthal never steps out of the historical frame to compare Lincoln’s time with our own, his story of how the pounding pressure of unrelenting partisan and regional conflict tore apart and reconfigured a seemingly immutable party system in the 1850s offers important insights into the ways today’s deep fissures might forge a new political alignment.

Wrestling with His Angel, which covers the years 1849 through 1856, is the second volume in a projected four-book series that amounts to a political life and times for Lincoln. Here Blumenthal very much stresses “the times.” Lincoln vanishes for long stretches; Stephen A. Douglas, Lincoln’s lifelong rival, dominates most of the narrative. That emphasis reflects the contrasting trajectories of the two men. The book captures Lincoln at low ebb, returning to a middling (at best) law practice in Illinois after serving a single term as a Whig in the House of Representatives.

Meanwhile, Douglas was at high tide. In these years, he was a dynamic (if coarse and sometimes booze-addled) young Democratic senator who seized the baton from the tiring Henry Clay to drive the Compromise of 1850 into law. Just four years later, Douglas passed the Kansas-Nebraska Act that repealed the seemingly impregnable Missouri Compromise and opened new states to slavery if their residents voted to allow it. After that triumph, Blumenthal writes, “Douglas had risen so far that Lincoln disappeared from his view. Five years gone from Washington, Lincoln was left to observe the tail of the comet.”

Yet Douglas’s seeming triumph precipitated the reversal of the two men’s fortunes. The cause of rallying opposition to the Kansas-Nebraska law, among the most misguided legislation ever passed by Congress, roused Lincoln “from his dormancy,” as Blumenthal writes, and returned him to center stage in Illinois politics. Just six years after Douglas’s great legislative victory, Lincoln soundly defeated him for the presidency, as the nominee of a new party that emerged precisely from the ferocious Northern backlash against the Kansas-Nebraska law and the attempt to impose a proslavery constitution on Kansas.

Many excellent books have recounted the destabilization of American politics and the march toward the Civil War in the 1850s, and many others have tracked Lincoln’s own journey toward greatness. Blumenthal inevitably operates in the shadow of the finest of these (such as David Potter’s magisterial The Impending Crisis, 1848-1861 or Eric Foner’s Free Soil, Free Labor, Free Men on the rise of the Republican Party). Blumenthal makes his contribution to this bulging literature by employing his skills as a political reporter to focus on politicians and their maneuvering. He provides captivating miniature portraits of the era’s dominant political figures, from a spidery, syphilitic Jefferson Davis scheming to strengthen the South as President Franklin Pierce’s secretary of war, to Missouri’s titanic Thomas Hart Benton thundering maledictions against his many enemies. (Benton, in floor debate, described Douglas’s Kansas-Nebraska Act as “a silent, secret, limping, halting, creeping, squinting, impish motion.”) Blumenthal applies a surprisingly bright coat of paint to the truncated presidency of Zachary Taylor, whom he portrays as a tough-minded unionist who stared down Southern threats before dying of cholera in office.

At times, Blumenthal gets lost in the weeds (literally, when recounting the battles of Thurlow Weed and William Seward with an array of rivals for control of the Whig Party in New York). His lengthy account of the political struggles between pro- and anti-slavery forces in Kentucky is vibrant but overwhelming in its dense detail. And while reviewers must always be careful about criticizing authors for not writing a different book, I believe Blumenthal would have benefited from a greater discussion of the economic forces that were also dividing a rapidly industrializing North from the agrarian South (and advantaging the former over the latter in the war to come).

Yet Blumenthal’s focus on the era’s political leadership offers its own rewards. It allows him to show how the sectional divide subsumed all other political issues and disputes. In the 1850s, slavery was the rock on which every institution in American life shattered. Churches, civic groups, even the two major national political parties, all sundered across the North/South boundary.

Much like Potter, Blumenthal shows how the intensifying conflict over slavery—or more precisely over whether slavery would be allowed to spread into new states—disrupted the alignment that had shaped U.S. politics for decades. Since the 1830s, American politics had revolved around the competition between Whigs and Democrats. The Whigs generally represented the merchant class and supported an activist role for government in creating the conditions for economic growth through initiatives such as building roads and canals, while Democrats rallied behind Andrew Jackson’s banner of smaller government, territorial expansion, and championing of the common (white) man. But those differences became secondary—first to leaders and then to voters—to the all-consuming question of whether to limit the expansion of slavery (especially after the Mexican-American War of 1848 forced Washington to decide whether slavery would be allowed in the vast new territories acquired in the conflict, including New Mexico and California).

With both parties divided between Northern and Southern wings, neither could meet the demands of many voters in the North for a party unambiguously opposed to the spread of slavery (if not its abolition in the states where it already existed).

The Compromise of 1850 had heightened the sectional tensions in each party, particularly by including the Fugitive Slave Act, which morally outraged many in the North. But the traditional partisan loyalties still survived that shock. Both parties stumbled through the presidential election of 1852 clinging to their old differences and hoping to sublimate the mounting tension over slavery’s future. That year, as Blumenthal pointedly notes, both the Democrat and Whig platforms endorsed the Fugitive Slave Act, effectively disenfranchising the many Northerners opposed to it.

For Lincoln, the 1852 election may have been the personal low point as he sought to promote the lackluster Whig nominee Winfield Scott while abiding his party’s silence on the issues that consumed him. “He argued for no principles, upheld no cause and offered no serious discussion of any issue,” Blumenthal writes of Lincoln’s limp electioneering that year. “He permitted not a glimmer to show of his inner turmoil over the problem of slavery, the conflict of North and South, and the country’s future.”

The breaking point for this fraying party system came just two years later when Douglas pushed through his Kansas-Nebraska Act. His aim was not specifically to expand slavery, but he was willing to allow its spread to advance his deeper goal: to organize those vast territories so they could become the route for a transcontinental railroad that he anticipated would both enrich him (he had a habit of commingling his legislation and investments) and propel him to the presidency. Douglas believed that shifting the debate over slavery’s extension to the individual states would suppress the North-South conflict and allow him to emerge along a different axis as the champion of an expanding and modernizing America. As Blumenthal vigorously writes, Douglas “advertised himself as the herald of the future, the maker of the new age and front-runner of his generation—the political engine of the piston-driven forces of modernization.”

In fact, the Kansas-Nebraska Act had the opposite effect. Rather than suppressing the regional conflict, the act furiously inflamed it. Its mandate for popular sovereignty was virtually an invitation to civil war, as anti- and pro-slavery forces descended on Kansas to control the writing of its constitution. By Douglas’s own count, more than 1,500 sermons were preached against him in New England churches after the law’s passage. In the election of 1854, 84 percent of all Northern House Democrats who voted for the law were defeated. That rout tilted the party’s balance of power decisively toward the South and pushed it even more toward a pro-slavery stance that, in a reinforcing cycle, further undermined its standing in the North.

Meanwhile, with its Southern elements supporting the Kansas-Nebraska Act while its Northern leaders recoiled, the Whig Party “shattered into pieces under the stress,” as Blumenthal writes. An array of anti-Nebraska, fusion, temperance, and nativist parties initially filled the void while Whig stalwarts like Seward and Lincoln tried to hold their party together. But by 1856, the Whigs were effectively defunct and the Republican Party had emerged as a Northern party clearly opposed to slavery’s expansion. Lincoln formally joined the party in May 1856, just days after a pro-slavery militia sacked the town of Lawrence, Kansas, and John Brown retaliated with a massacre of five pro-slavery men in Pottawatomie Creek. “Each and every one of Douglas’s clever maneuvers would bring slavery to the forefront again,” Blumenthal concludes, “but on a basis more contentious than ever.”

In this rising conflict, Lincoln rediscovered his purpose. In a preview of their epic confrontations during the 1858 Senate race, Lincoln trailed Douglas around Illinois during the 1854 election. Though the two never directly debated, Lincoln’s speeches offered the first rough drafts of the piercing arguments he would deploy in 1858 against Douglas’s morally agnostic approach to slavery. (Lincoln’s core argument in 1854 was that Douglas’s claim to support popular sovereignty required listeners to deny the humanity of the slaves: “[I]f the negro is a man, is it not to that extent, a total destruction of self-government, to say that he too shall not govern himself?”) It was in refuting Douglas that Lincoln awakened his own greatness—a metamorphosis sure to dominate Blumenthal’s next volume.

Lincoln was a singular figure who combined moral courage with shrewd tactical insight, bottomless perseverance, and unmatched literary gifts. His personal story offers limited guidance to succeeding generations because the hyperactive modern political system is not likely to produce such a transcendent figure again—and probably would not recognize him or her if it did.

Yet the crisis of the 1850s that Blumenthal recreates so vividly here remains worthy of study because it represents the last time a major new party emerged in the United States. The Republican Party took root in the space between the anachronistic terms of political debate between Whigs and Democrats and the evolving nature of the nation’s most pressing political conflict. As the sectional struggle washed over the old political boundaries, the Republican Party coalesced the forces opposed to slavery that had been submerged in both of the existing parties. Sweeping away older issues and alignments, the GOP’s rise refocused the political debate onto the central issue of the time (the fate of slavery) and reset the partisan configuration around society’s most important division (the North/South regional split).

The mismatch isn’t as great today, but once again the nature of the party competition no longer fully reflects the country’s actual divisions. Democrats and Republicans mostly think of themselves in a mold stamped during the New Deal, with Democrats as the party of working people and Republicans as the party of the economic elite. In fact, the parties now separate less along class lines than in their attitudes toward the fundamental demographic, cultural, and economic changes remaking American society. Democrats mobilize what I’ve called a “coalition of transformation” that revolves primarily around millennials, minorities, and college-educated whites who are generally the most comfortable with increasing diversity, greater social inclusion, and the transition to a post-industrial, globalized (and low-carbon) economy. Republicans rely on a competing “coalition of restoration” centered on older, blue-collar, non-urban, and evangelical whites most resistant to these same changes.

By appealing more explicitly to white racial identity than any national figure since George Wallace, Donald Trump has both exploited and intensified the separation of the parties along these cultural and racial lines. In 2016, Trump won a higher share of non-college white voters than any candidate in either party since Ronald Reagan in 1984, while facing huge deficits among minorities and millennials and nearly becoming the first Republican nominee in the history of polling to lose most college-educated whites. Trump’s unflinchingly polarizing and racially divisive agenda is increasing the pressure on the outliers in each coalition: the remaining culturally conservative blue-collar white Democrats drawn toward aspects of Trump’s insular nationalism, and the white-collar Republicans who like the party’s anti-tax, anti-regulation agenda but are uneasy with Trump’s repeated gestures to white racial resentment.

Amid his daily chaos, Trump is now losing support on all sides. But if Trump can stabilize his presidency he may well lure more blue-collar whites (though probably not working-class minorities) from the Democrats at the price of driving more white-collar whites toward them. The end result might be two parties contrasted even more clearly than they are today by their attitudes toward social and economic change, and perhaps a serious third-party contender in 2020 filling the space between them. As Blumenthal demonstrates in his compelling history of Lincoln, Douglas, and the Cold War between North and South through the 1850s, once such a process of partisan recombination begins, no one can be entirely sure where it will end.